This is an easy way to get some quick and green satisfaction. Remember if you do this, you will need to pay attention to aspect. North facing walls are best, but anyplace that doesn't get sun fried will work. Moss is a sensitive medium. Best done with the cover of night, unless of course you have permission. And we all will right... ?

Or...
Just draw something cool and cut out the negative space. Silhouettes are VERY easy to do!

For street art, just fill a container with your moss solution (recipe below), and take a roller brush. Hold the stencil
up to the wall and roll the moss juice into the stencil. Not too much, drips are for amateurs!!! (obviously there are
major exceptions to this rule). The number one thing is to have a great time altering your environment!